Center input from stdin in terminal or return 1 if it doesn't fit

center.sh

#!/usr/bin/env bash

# Print n blank lines
#
# @param 1 - number of blank lines to print (default 1)
blanks() {
	local I
	for (( I=${1:-1}; I--; ))
	do
		echo
	done
}

# Horizontally and vertically center input from stdin in terminal
center() {
	local TMP
	TMP=$(mktemp "/tmp/${0##*/}.XXXX")
	local WIDTH=0 HEIGHT=0
	while read -r
	do
		# there's wc -L on BSD
		local L=${#REPLY}
		(( L > WIDTH )) && WIDTH=$L
		(( ++HEIGHT ))
		echo "$REPLY"
	done > "$TMP"
	local LINES=${LINES:-$(tput lines)}
	local COLUMNS=${COLUMNS:-$(tput cols)}
	local SPACES=' '
	while (( ${#SPACES} < COLUMNS ))
	do
		SPACES=$SPACES$SPACES
	done
	local VPAD=$(( (LINES - HEIGHT) / 2 ))
	local HPAD=$(( (COLUMNS - WIDTH) / 2 ))
	if (( VPAD < 0 )) || (( HPAD < 0 ))
	then
		return 1
	fi
	(( VPAD > 0 )) && blanks "$VPAD"
	while read -r
	do
		echo "${SPACES:0:$HPAD}$REPLY"
	done < "$TMP"
	rm -f "$TMP"
	(( VPAD > 0 )) && blanks "$VPAD"
}

if [ "${BASH_SOURCE[0]}" == "$0" ]
then
	center
fi